1. Bring the engine to operating temperature.
2. Remove the oil pressure switch/sending unit.
3. Install a tee adaptor between the oil pressure switch/sending unit and cylinder case passage fitting.
4. Connect a pressure gauge that reads from 0 to 1034 kPa (0 to 150 psi) to the tee adaptor (see Figure 3-17).
5. Start and run the engine, observing the gauge reading:
• If the gauge reading at idle speed is lower than 69 kPa (10 psi), go to step 6.
• If the gauge reading at 2,000 rpm is lower than 276 to 310 kPa (40 to 45 psi), go to step 6.
• If the gauge reading at any engine speed is higher than 552 kPa (80 psi), go to step 7.
6. Remove the pressure gauge and tee adaptor and install the oil pressure switch/sending unit.
7. Check the oil pressure between the pump and the filter, using tool J 25087-C (see Figure 3-18):
• If the gauge reading at idle speed or 2,000 rpm is lower than the specification, inspect the following parts:
– Oil pump and pressure regulator valve
– Crankshaft bearings for excessive clearance
– Camshaft bearings for excessive clearance
– Hydraulic lifters for excessive bore clearance
– Cylinder case passages for internal leaks
• If the gauge reading at idle speed or 2,000 rpm meets the specification, inspect the following parts for
restriction:
– Oil cooler and bypass valve
– Oil filter and bypass valve
– Cylinder case passages
8. Remove the oil pump and inspect the pressure regulator valve for binding related to excessively high oil
pressure (replace the oil pump, if needed).
